“Schrödinger’s SRM”- Guest Post- Duncan McLaren -University of Lancaster

In an ideal world, the only people prepared to give stratospheric sulphate aerosol injection a second glance are those climate deniers who have exhausted every other argument they have against mitigation.

We are largely familiar with ideas of cutting emissions (mitigation) and adapting to the impacts of climate change (by, for instance, building better flood defences). We also know that states, businesses and individuals face a whole range of incentives to keep emitting and underperform on mitigation, with the result that the world is badly off course for meeting the political goal of restricting warming to 2oC, rather being set for warming of 4oC or more by 2100.

In such circumstances anything that further discourages commitment to mitigation is clearly a ‘bad thing’, right? And what if that thing were to also generate new risks by creating the possibility of a massive acceleration in global warming over a 5-10 year period at some unspecified future date (the so-called ‘termination effect’), changing regional climates in unexpected and unpredictable ways, while prolonging the hole in the ozone layer by 30 years, marginally increasing levels of acid precipitation and reducing the effectiveness of solar power?

One might reasonably consider such a technology unethical, and even perhaps evil. And indeed stratospheric sulphate aerosol injection (a form of “solar radiation management” geoengineering, or ‘SRM’) might appear so. In an ideal world the only people prepared to give the technique a second glance are those climate deniers who have exhausted every other argument they have against mitigation: slowly and sequentially retreating from denying the existence of climate change to admitting it, but only as a natural process; then acknowledging human causation, yet claiming it would be good for us; and subsequently – like Bjorn Lomborg – accepting it would be bad, but that there are many other more important things to spend political and financial capital on. From there, the only option left to resist mitigation is geoengineering, and the stratospheric sulphate variety of solar radiation management (SRM) is the apparently cheap and cheerful choice.

Not only are such advocates supportive of SRM for the reason of resisting mitigation (and the perceived costs of regulation or carbon taxation), but political leaders are receptive to their arguments. It’s not just tea-party Republicans in the United States, and their doppelgangers like Tony Abbott in Australia and Stephen Harper in Canada, but politicians across the spectrum bruised and battered by political battles over climate change, that would welcome a coherent case for easing off on mitigation in favour of something politically and financially cheaper. The idea that, faced with the chance to take action on climate change without doing the political and practical dirty work to cut emissions, decision makers might ease off on mitigation in favour of researching and developing a geoengineering short cut, is commonly called ‘moral hazard’. Few researchers reject the existence of such a pressure, although they use various terms to describe it.

Yet support for SRM – at least for research – comes from other quarters too. Climate scientists and activists, recognising the physical inertia in the climate system, and the political inertia in the world’s largest economies are increasingly worried that climate change may soon, if not already, be beyond control by mitigation and adaptation, putting billions at risk from food insecurity, water stress, rising sea levels and other climate impacts – with the worst effects arising for the already worst-off and most vulnerable. They rightly ask: at what point do we accept that the world will need something more than better mitigation; at what point do we prepare for the worst, and research SRM in the detail needed to be able to minimise its undesirable side effects and risks.

Yet support for SRM – at least for research – comes from other quarters too.

From this perspective developing SRM might not only be ethical, it might be the only genuinely ethical option. Yet the moment we accept these arguments, we make it immensely more likely that SRM will need to be used, as we empower the deniers and the ‘easy-option’ politicians, and the businesses keen to wring every last drop of profit from fossil fuels to resist and reduce mitigation. Some researchers also introduce limited economic arguments that suggest it is rational to reduce mitigation effort in the presence of SRM (even though it is only in a world with SRM, that we face the risk of the termination effect).

So the space between ethical SRM and its evil twin is infinitesimal – thinner than a sheet of paper. Until such point as it is essential, the ethical position appears to be to resist any plausible development of SRM – as campaign groups such as ETC have done. But once that point is past, any resistance becomes ethically untenable.

The problem is that unless stakeholders and decision makers can somehow discuss SRM sensibly and safely, without triggering the effects of moral hazard it is impossible that we will ever know if its deployment genuinely could be safe, practical and ethical.

A possible answer is Schrodinger’s SRM: just as in Schrodinger’s thought experiment the infamous cat existed in a state of quantum indeterminacy, both and neither alive and dead; we should see SRM as in a state of indeterminacy – both and neither ethical and evil. This could give researchers a safe house or ‘grey zone’ where, with careful attention to the design of research projects we could properly investigate the many scientific, political and cultural uncertainties and unknowns, and seek ways to acknowledge, limit and mitigate the unknowables that are likely to remain without exacerbating moral hazard. How that ‘grey zone’ is designed in practice is a question for another day, but without it we may open the box in 2035 or 2055, and find not ethical SRM, but its evil twin waiting for us.


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Duncan McLaren is a part time PhD student at Lancaster, UK. Alongside his PhD studies, on the justice implications of geoengineering, he consults and advises in a range of sustainable development, energy and climate change issues. Amongst other roles he served on the UK Research Councils’ stage-gate panel for the Stratospheric Particle Injection for Climate Engineering (SPICE) project review and is a member of the Integrated Assessment of Geoengineering Potential (IAGP) project advisory group.  Duncan’s blog can be found here


The Washington Geoengineering Consortium does not necessarily endorse the ideas contained in this or any other guest post. Our aim is to provide a space for the expression of a range of perspectives on geoengineering.